The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Electrophoretic deposition coating (“E-coating”) is a coating process that is used to deposit an organic film by an electrical charge. The coating in some applications is used as a primer for corrosion protection in automotive applications, and more specifically for a Body-in-White (BIW).
Referring to FIG. 1, an exemplary straight dipping method for high volume E-coating of an automotive Body-in-White (BIW) is illustrated, in which the automotive BIW 10 is conveyed through a processing fluid tank 12 in a conveying direction C. The vehicle BIW 10 maintains a constant position while being conveyed through the processing fluid tank 12. For example, the vehicle BIW 10 maintains a similar orientation to that of which the vehicle is designed to be used in. Challenges and/or inefficiencies associated with the straight dipping method include: hard to reach surface areas or parts of the vehicle BIW 10 not being reached by the processing liquid, such as recesses, resulting in uncoated metal, uneven film coverage, and a film layer thickness below standards; increased air entrapment resulting in discontinuity of the film being applied; and increased likelihood of excess E-coat being applied to susceptible surface areas, thereby creating uneven film coverage. These inefficiencies contribute to improper finish and decreased corrosion protection.
Referring to FIG. 2, another exemplary dipping method for high volume E-coating of a BIW is illustrated, often referred to as roll dipping. In this method, the BIW 10 is conveyed through the processing liquid tank 12 in a conveying direction C and is tumbled, or rolled around a lateral axis Y (shown in and out of the page), while submerged in the processing fluid tank 12. Challenges and/or inefficiencies with the roll dipping method include: high loading conditions that can permanently deform parts of the vehicle BIW; and depths of the processing tank need to be deeper than the length of the vehicle BIW to maintain full submersion of the vehicle BIW while being rotated around its lateral axis Y. These inefficiencies increase overall waste and production costs.
The inefficient corrosion protection, finish, and increased production costs of known E-coating processes, among other issues related to the coating of an automotive BIW, are addressed by the present disclosure.